A Visible Spectrophotometric Method for the Estimation of Tapentadol


K. Vanitha Prakash, Y. Kranti Kumar and Guthi Lavanya

Dept. of Pharmaceutical Analysis, SSJ College of Pharmacy, V.N. Pally, Gandipet,

Hyderabad - 500 075, Andhra Pradesh, India.

*Corresponding Author E-mail: prakash.karnam@gmail.com




A simple, economical, precise, reliable and reproducible visible Spectrophotometric method has been developed for the estimation of Tapentadol in bulk as well as in tablet formulations. This method is based on the formation of Blood red colored chromogen with 1,10Phenanthroline which shows maximum absorption at 510nm. The absorbance-concentration plot is linear over the range 10-100µg/ml. Results of analysis were validated statistically. Recovery studies were also performed. The proposed method is economical, accurate precise and sensitive for the estimation of Tapentadol in bulk drug and its formulation.






Tapentadol, (–)-(1R,2R)-3-(3-dimethylamino-1-ethyl-2-methyl-propyl)-phenol hydrochloride (tapentadol HCl), with respect to its in vitro characteristics and its analgesic, antihyperalgesic, and antiallodynic properties in rat and mouse models of acute and chronic pain. Tapentadol, a centrally acting synthetic analgesic, received initial U.S. approval in 20081 and was then placed into the schedule II category of the Controlled Substances Act in May of 20092. The drug is a novel, centrally acting oral analgesic with a dual mode of action that has demonstrated efficacy in clinical application. It is suggested that the broad analgesic profile of tapentadol and its relative resistance to tolerance development may be due to a dual mode of action consisting of both MOR activation and NE reuptake inhibition3. Few HPLC chromatographic methods are reported4-7. Only few spectrophotometric methods were reported for estimation of tapentadol8-10.


Structure of Tapentadol




Elico double beam Ultra Violet- Visible double beam Spectrophotometer SL-244 with 1cm

matched quartz cells was used for all spectral measurements.


Preparation of Reagents:

All chemicals used were of analytical reagent grade.

1      Preparation of 0.01 M 1,10 phenanthroline(198.22 g mol-1)for 100ml.Weigh 0.198gms of 1,10 phenanthroline in 100ml of 0.1N HCL and  make up to 100ml.

2      Preparation of 0.003M Ferric chloride(MWT-162.2g) solution Weigh 0.162gms of ferric chloride, dissolve in distilled water and make up to 100ml

3      Preparation of 0.2M Ortho phosphoric acid (MWT-98gms) solution Weigh 1.3ml of Ortho phosphoric acid, dissolve in distilled water and make up to 100ml.

4      Preparation of standard solution of 100mg in 100ml stock solutionWeigh 100mg of bulk drug (Tapentadol) and dissolve in distilled water and make up to 100ml to give a stock solution of 1000 mcg/ml.


Assay Procedure:

Aliquots of standard drug solution of Tapentadol (0.5-3.0mL) (200 µg/mL) were taken and transferred into series of graduated test tubes. To each test tube add 2 mL of 1,10 phenanthroline reagent,1ml of ferric chloride were added. The test tubes were allowed to stand in waterbath at700C for 20min.The test tubes were then  cooled to room temperature and then 2 mL of orthophosphoric acid was added, the solutions were made upto 10 mL with distilled water. The absorbance of blood red coloured chromogen was measured at wavelength of 510nm against reagent blank and a calibration curve was constructed. The absorbance of the solution was measured and the amount of Tapentadol was determined by referring to the calibration curve.


Preparation of sample solution:

10 tablets of Tapentadol (TYDAL-100mg) were accurately weighed and powered. Tablet powder equivalent to 270mg of Tapentadol was dissolved in 100 mL of distilled water, sonicated for 15min and filtered. The solution was suitably diluted and analyzed as given under the assay procedure for bulk sample. The analysis procedure was repeated three times with Tablet formulations and the results of analysis for the method is shown in Table:         1..


Recovery Studies:

To ensure the accuracy and reproducibility of the results obtained, known concentration of the pure drug solution was added to the previously analyzed formulated solution samples and these samples were reanalyzed by the proposed method and also preformed recovery studies. The percentage recoveries, thus obtained for method is given in Table: 2.






λmax (nm)


Beers law limit µg/mL


Molar Absorbtivity

(μgms/cm2/0.001Absorbance unit)


Sandell"s Sensitivity

(μgms/cm2/0.001Absorbance unit)


Regression Equation y






Correlation Coefficient


Precision(% relative standard deviation)


Standard error of estimate




The optimum conditions were established by varying one parameter at a time and keeping the others fixed and observing the effect on absorbance of chromogen. The Method is based on the reduction of Ferric chloride to ferrous form by the drug, which forms complex with 1,10 Phenanthroline to yield blood red colored chromogen, having absorbance maximum at 510 nm shown in  Fig 1. The linearity was found to be in the concentration of 10-100 mcg/mL and linearity calibration curve is shown in Fig 2. The colored chromogen was stable for 2 hrs.


Statistical analysis was carried out and the results were found to be satisfactory .Relative standard deviation values were low indicating the reproducibility of the proposed methods. Recovery studies were close to 100% that indicates the accuracy and precision of the proposed methods. The optical characteristics such as absorption maxima, Beer’s law limits, molar absorptivity, Sandell’s sensitivity and other parameters are presented in Table: 2

This new procedure for the spectrophotometric determination of Tapentadol described in this work is simple, rapid and cost-effective with high accuracy and precision, when compared with previously reported procedures. It could find application as a convenient technique for the in-process control analysis of Tapentadol in bulk and its pharmaceutical formulations.


Figure 1: Absorption Spectrum of Tapentadol with 1,10 Phenanthroline


Concentration µg/ml

Figure 2: Linearity calibration curve of Tapentadol with 1,10 Phenanthroline



TABLE-2: Assay of Tapentadol in Tablet Formulations:

Tablet Formulation

Labelled Amount(mg)

*Amount    Obtained(mg)

by Proposed Method

% **Recovery by the Proposed Method



97.8 ±2

98.73 ±2



98.3 ±1

99.01 ±1



99.5 ±1

101.17 ±1

*Average of three determination .

**After spiking the sample.



The authors are grateful to MSN Laboratories, Hyderabad, India for proving a gift sample of Tapentadol and to the Management of SSJ College of Pharmacy, Hyderabad, A. P. India for providing the necessary facilities and chemicals.



1        Physicians’ Desk Reference, 64th ed. PDR Network, LLC, Montvale, NJ, 2009, pp 2643–2648.

2.       Schedules of controlled substances: placement of tapentadol into schedule II. Final rule. Fed. Regist. 74(97): 23790–23793 (2009).

3        Thomas M. Tzschentke, et al. (–)-(1R,2R)-3-(3-Dimethylamino-1-ethyl-2-methyl-propyl)-phenol Hydrochloride (Tapentadol HCl): a Novel μ-Opioid Receptor Agonist/ Norepinephrine Reuptake Inhibitor with Broad-Spectrum Analgesic Properties. Journal of Pharmacology and Experimental Therapeutics 2007; 323:265-276.

4        C. Coulter, et al. Determination of tapentadol and its metabolite N-desmethyltapentadol in urine and oral fluid using liquid chromatography with tandem mass spectral detection, J. Anal. Toxicol. 34 (2010) 458–463.

5        J.A. Bourland, et al .Determination of tapentadol (Nucynta®) and N-desmethyltapentadol in authentic urine specimens by ultra-performance liquid chromatography-tandem mass spectrometry, J. Anal.Toxicol. 34 (2010) 450–457.

6        Validation of Analytical procedures: Text and Methodology; International Conference on Harmonization: Draft Revised Guidance on Q2 (R1); Federal Register, Vol. 60, March 1, 1995.

7        Omkar D, et al. Development and Validation of RP- HPLC, UV-Spectrometric and Spectrophotometric Method for Estimation of Tapentadol Hydrochloride in Bulk and in Laboratory Sample of Tablet Dosage Form, Journal of Chemical and Pharmaceutical Research, 2012, 4(9):4134-4140.

8        Bysani Suresh Babu, et al Development and validation of UV-Visible spectrophotometric method for the determination of Tapentadol hydrochloride from tablet dosage form.

9        B. Pavan Adithya. Spectrophotometric estimation of tapentadol in bulk and its pharmaceutical formulation, Journal of Chemical and Pharmaceutical sciences.

10.    Mobrouk et al, Spectrophotometric Methods for Determination of Tapentadol  Hydrochloride, Journal of Applied Pharmaceutical Science; Mar2013, Vol. 3 Issue 3, p122.




Received on 12.09.2013       Modified on 28.09.2013

Accepted on 29.10.2013      © RJPT All right reserved

Research J. Pharm. and Tech. 6(12): Dec. 2013; Page 1333-1335